MRF421 Equivalent & Substitute Parts

Part Overview

The MRF421 is an RF Transistor NPN rated for 20V collector-emitter breakdown voltage with 20A maximum collector current and 100W maximum power dissipation. Manufactured by MACOM Technology Solutions, this chassis mount device (211-11, Style 2 package) is designed for high-power RF applications. The part maintains Active product status with 1005 units in current inventory and full ROHS3 compliance.

Substitute parts become necessary when the MRF421 reaches end-of-life, when supply constraints occur, or when application requirements shift toward different frequency bands or power levels. The substitute parts listed below provide functional alternatives across varying specifications while maintaining NPN transistor topology and RF performance characteristics.

Substiute Parts

MRF421

MACOM Technology SolutionsIn Stock: 1030MRF421 Datasheet

Current PartRFQ

2SC5347AE-TD-E

onsemiIn Stock: 41392SC5347AE-TD-E Datasheet

MFR RecommendedRFQ

BFP640ESDH6327XTSA1

Infineon TechnologiesIn Stock: 1267BFP640ESDH6327XTSA1 Datasheet

MFR RecommendedRFQ

BFR193L3E6327XTMA1

Infineon TechnologiesIn Stock: 990BFR193L3E6327XTMA1 Datasheet

MFR RecommendedRFQ

MAX2601ESA+

Analog Devices Inc./Maxim IntegratedIn Stock: 2334MAX2601ESA+ Datasheet

MFR RecommendedRFQ

SMMBTH10-4LT3G

onsemiIn Stock: 1081SMMBTH10-4LT3G Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the MRF421 is determined by the following critical parameters:

Primary Substitution Criteria:

• Transistor Type: NPN topology required
• Voltage Rating: Collector-emitter breakdown voltage must equal or exceed application requirements
• Current Capability: Maximum collector current must support circuit demands
• Power Dissipation: Maximum power rating must accommodate RF output levels
• Mounting Configuration: Physical form factor and thermal management approach

Secondary Compatibility Factors:

• Frequency Response: Transition frequency determines high-frequency performance capability
• Gain Characteristics: dB gain and hFE values affect circuit biasing and impedance matching
• Package Type: Determines PCB integration method and thermal interface requirements
• Compliance Status: RoHS3 and REACH certifications ensure regulatory alignment

The substitute parts listed below are grouped by their electrical performance envelope relative to the MRF421 baseline. Each substitute maintains NPN configuration and ROHS3 compliance but operates within different voltage, current, and frequency domains.

Parameter Comparison

Engineering Selection Recommendations

Active Product Status Preference: BFP640ESDH6327XTSA1, BFR193L3E6327XTMA1, MAX2601ESA+, and SMMBTH10-4LT3G maintain Active product status. The 2SC5347AE-TD-E carries Obsolete designation and should be avoided for new designs unless legacy system compatibility is mandatory.

Voltage Rating Alignment: The MRF421 operates at 20V maximum collector-emitter breakdown. Substitute selection depends on application voltage requirements:

• SMMBTH10-4LT3G (25V rating) accommodates higher voltage margins
• MAX2601ESA+ (15V rating) operates within reduced voltage envelope
• BFR193L3E6327XTMA1 and 2SC5347AE-TD-E (12V rating) require lower voltage operation
• BFP640ESDH6327XTSA1 (4.7V rating) operates in low-voltage RF circuits only

Current and Power Capability: The MRF421 delivers 20A at 100W maximum power. No substitute part matches this high-current, high-power specification. Substitute selection requires application redesign:

• MAX2601ESA+ (1.2A, 6.4W) provides moderate power capability for mid-range RF applications
• BFR193L3E6327XTMA1 (80mA, 580mW) and 2SC5347AE-TD-E (150mA, 1.3W) serve lower-power RF stages
• BFP640ESDH6327XTSA1 (50mA, 200mW) and SMMBTH10-4LT3G (225mW) operate in signal-level RF circuits

Frequency Performance:

• BFP640ESDH6327XTSA1 (46GHz transition frequency) enables ultra-wideband and millimeter-wave applications
• BFR193L3E6327XTMA1 (8GHz) supports microwave and cellular band RF stages
• 2SC5347AE-TD-E (4.7GHz) and MAX2601ESA+ (1GHz) address lower-frequency RF requirements
• SMMBTH10-4LT3G (800MHz) operates in VHF/UHF frequency bands

Compliance and Regulatory Alignment: All substitute parts maintain ROHS3 compliance. BFP640ESDH6327XTSA1, BFR193L3E6327XTMA1, and MAX2601ESA+ carry REACH Unaffected status, confirming regulatory alignment for global supply chains.

Mounting and Thermal Considerations: The MRF421 uses chassis mount configuration for direct thermal interface. All substitute parts employ surface mount packaging (SOT-23-3, SOT-343, SOT-883, SOIC-EP, TO-243AA), requiring PCB thermal management design. Thermal interface requirements differ significantly from the original chassis mount approach.

Frequently Asked Questions (FAQ)

Q: Can the MRF421 be directly replaced with any of these substitute parts?

A: Direct replacement is not possible. The MRF421 operates at 20A and 100W, while all substitute parts operate at significantly lower current and power levels. Substitution requires circuit redesign to accommodate reduced power capability and different mounting configurations. Frequency response, voltage ratings, and gain characteristics also differ substantially across the substitute options.

Q: Which substitute part most closely matches the MRF421 electrical performance?

A: No substitute part provides equivalent electrical performance across all parameters. MAX2601ESA+ offers the highest power capability (6.4W) and current rating (1.2A) among the substitutes, making it suitable for moderate-power RF applications. However, it operates at 15V maximum voltage and 1GHz transition frequency, differing from the MRF421 baseline. Application-specific requirements determine the most appropriate substitute.

Q: Are all substitute parts suitable for new product designs?

A: Four of the five substitute parts maintain Active product status: BFP640ESDH6327XTSA1, BFR193L3E6327XTMA1, MAX2601ESA+, and SMMBTH10-4LT3G. The 2SC5347AE-TD-E carries Obsolete designation and should not be selected for new designs. Active status parts ensure long-term supply availability and manufacturing support.

Q: What are the key differences in package configuration?

A: The MRF421 uses chassis mount 211-11 Style 2 package for direct thermal coupling to external heat sinks. All substitute parts employ surface mount packages: SOT-23-3 (SMMBTH10-4LT3G), SOT-343 (BFP640ESDH6327XTSA1), SOT-883 (BFR193L3E6327XTMA1), SOIC-EP (MAX2601ESA+), and TO-243AA (2SC5347AE-TD-E). PCB-based thermal management becomes necessary, requiring modified circuit board design and thermal via patterns.

Q: How do frequency ratings affect substitution decisions?

A: Frequency response determines application suitability. BFP640ESDH6327XTSA1 (46GHz) addresses millimeter-wave and ultra-wideband circuits. BFR193L3E6327XTMA1 (8GHz) supports microwave and cellular band applications. MAX2601ESA+ (1GHz) and 2SC5347AE-TD-E (4.7GHz) serve lower-frequency RF stages. SMMBTH10-4LT3G (800MHz) operates in VHF/UHF bands. Application frequency requirements must align with substitute part transition frequency specifications.

Q: What compliance certifications apply to all substitute parts?

A: All five substitute parts maintain ROHS3 compliance. BFP640ESDH6327XTSA1, BFR193L3E6327XTMA1, and MAX2601ESA+ carry REACH Unaffected status. The 2SC5347AE-TD-E and SMMBTH10-4LT3G do not list REACH status in provided specifications. Regulatory requirements for target markets determine compliance necessity.

Q: Can voltage rating differences affect circuit operation?

A: Yes. The MRF421 operates at 20V maximum collector-emitter breakdown. Substitute parts range from 4.7V (BFP640ESDH6327XTSA1) to 25V (SMMBTH10-4LT3G). Application bias voltage and supply voltage must not exceed the selected substitute part's voltage rating. Lower-rated parts require circuit redesign to operate within reduced voltage envelopes. Higher-rated parts provide voltage margin but may not optimize performance in lower-voltage applications.

Q: How do current gain (hFE) specifications influence substitution?

A: DC current gain (hFE) affects biasing network design and impedance matching. The MRF421 specifies 10 hFE minimum at 5A and 5V. Substitute parts range from 70 to 120 hFE at significantly lower current levels (4mA to 250mA). Higher hFE values in substitute parts require reduced base drive current, affecting bias resistor selection and overall circuit efficiency. Gain variation across frequency (dB gain range) also influences frequency response characteristics.

Q: What inventory considerations apply to substitute part selection?

A: Current inventory levels are: MRF421 (1005 units), 2SC5347AE-TD-E (4129 units), BFP640ESDH6327XTSA1 (1225 units), BFR193L3E6327XTMA1 (882 units), MAX2601ESA+ (2300 units), and SMMBTH10-4LT3G (994 units). Inventory availability supports immediate procurement for all parts. However, the 2SC5347AE-TD-E Obsolete status may indicate declining future availability despite current stock levels.